The Gothic Rose Window
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COMPUTER-AIDED MODELING APPLIED TO ARCHITECTURAL KNOW-HOW: THE GOTHIC ROSE WINDOW SUBMITTED: August 2005 REVISED: November 2005 PUBLISHED: May 2006 at http://itcon.org/2006/26/ EDITOR: J. M. Kamara Nathalie Charbonneau, Ph.D. Candidate École d’Architecture, Faculté de l'Aménagement, Université de Montréal, (Québec) Canada email: [email protected] Dominic Boulerice, Ph.D. Candidate Department of Art History and Communication Studies, McGill University, Montréal, (Québec) Canada email: [email protected] David W. Booth, Associate Professor Département d’Histoire de l’art et d’études cinématographiques, Université de Montréal, (Québec) Canada email: [email protected] SUMMARY: This paper explains the parameters and methodology at the heart of an ongoing research project that seeks to verify whether one can trace back the genesis of any given artefact or work of art by means of computer-aided modeling. In its endeavour our Montréal-based research team aims to initiate and propose novel methods of modeling design processes. This approach is exemplified by a case study dealing with rose tracery designs adorning Gothic cathedrals of 12th and 13th Century Île-de-France. A computerized model re- enacting their design process was developed along with an interface enabling the translation of the designer’s intentions into a virtual design space. The stated goal of this research project is to evaluate empirically to what extent our modeling strategies can grasp a given artefact as a logical and articulate ensemble. Furthermore, we seek eventually to determine whether this kind of software programme would prove an indispensable tool in the development of the architectural designer’s cognitive abilities. KEYWORDS: architectural modeling, computer-aided design, architectural know-how, functional programming. 1. INTRODUCTION In the broad field of architecture, computers are currently employed to generate graphical representations of design concepts. Despite their ubiquitous presence within the discipline it is unlikely that computers are really put to use at their full capacity. Can computers be more than digital drafting tables? After all, computers literally offer a whole virtual world that can unfold in time in a non-linear fashion. With the computer one should be able to place an architectural concept before the mind not only at certain fixed moments in its development, but also in the entirety of its relational process of generation, from the mind of its creator to its material execution. Like any human artefact, a building is the result of a process, a process that is never directly accessible as a whole because its various stages cease to exist when their productive function has been fulfilled, their effects often felt only in the final product. Our purpose is not to question the value of graphical representation, the traditional medium of communication favoured by art and architecture for many centuries, but simply to ask whether computers can go beyond traditional graphical representation stricto sensu? Our thesis is straight forward: we argue that with certain of the technological means available today we are not always obliged to content ourselves with fixed graphical representations of design ideas isolated from one another and from formative factors in time and space. Indeed, this has been the premise of the research project this paper reports. There, as here, we explore the possibility of a computerized simulation of the various phases of an actual architectural design process by means of an historical case study, the rose window configurations of Gothic church architecture. ITcon Vol. 11 (2006), Charbonneau et al, pg. 361 2. THE PROCEDURAL MODEL Before it is materialized, an architectural idea is established, developed, and refined in the mind of the designer, though there is no trace left whatsoever of this internal mental process. Behind any given monument or artefact stands a creative process of great complexity and about which we are naturally curious. In our research we seek to determine whether the creation of any given artefact or work of art can be recovered and re-presented as a dynamic process, i.e., in its integral wholeness, by means of computer-aided modeling (Tidafi, 1996, De Paoli, 1999). In recent years, our research team within the CAD Research Group (GRCAO), in the School of Architecture of the Université de Montréal, has sought to initiate and propose novel methods of modeling design procedures that would enable the innovative use of accumulated architectural know-how. We have explored the possibilities of developing computer software programmes that would allow the modeling of an artefact based on the know-how that produced it, thus integrating knowledge relating to its construction as well as to its formal design. Based on a procedural model, that is, a model describing an object’s inherent, productive compositional logic, our modeller can not only seize and recount every step of its design process; it also permits the modeling of typological variants. Above all, such a programme not only allows, but actively encourages, interaction at all moments of the design process, particularly during visualization and manipulation of the model in the virtual design space. 3. THE GOTHIC ROSE WINDOW Along with pointed arches and flying buttresses, medieval rose windows have come to epitomize the Gothic cathedral. From the fairly modest-sized oculi – mere roundels often left unadorned – of Romanesque and Early Gothic churches, to the colossal tracery networks spanning some 12 metres on the Western façade of Chartres Cathedral, Gothic rose windows bear witness to the great technological know-how of medieval builders (Fig. 1). FIG. 1: Western rose window, Chartres Cathedral, photograph by Dominic Boulerice. Tracery networks evolved from plate to bar tracery: once pierced panels of stone, they literally became thin stone bars skilfully designed and assembled to form a decorative structure supporting stained glass panels. The Early Gothic and Rayonnant (12th- to 13th-century) rose tracery designs are made up of mullions, colonnettes and ITcon Vol. 11 (2006), Charbonneau et al, pg. 362 voussoirs arranged according to a geometric pattern that reveals a great deal about their compositional logic. It must be borne in mind that our project seeks to trace in reverse the genesis of a given artefact, the Gothic rose window, employing a procedural model. The point of this effort is to understand, describe and model a design process that today is, at best, little-known and must be deduced from various sources, primarily the design product itself. In so doing we seek to develop a method that describes an artefact in an integral manner by modeling the relational sequence of decisions taken by its designer(s), and thereby to reveal the compositional logic that informs the artefact or work of art. Gothic rose tracery designs lend themselves particularly well to this type of compositional analysis: they were devised using straight-forward practical geometry and are basically two-dimensional in conception. They also comprise a well-circumscribed aspect of medieval design whose principles of design would have been readily grasped by practitioners who possessed little in the way of theoretical knowledge. Rose window design was not, however, an effortless art. One must never lose sight of the fact that, while these circular stone tracery networks were designed in regard of their aesthetic, formal and symbolic effects, they were also obliged to respond to mechanical problems of support and load in a manner consistent with the well-known daring of their creators. All of these imperatives of contemporary design needed to be adroitly juggled in the conception of a window tracery. Certainly the creation of such designs called for deep experience, crafty calculation, vast knowledge and outstanding comprehension of the application of structural constraints in the general context of ornamental effect, as Viollet-le-Duc correctly pointed out in his Dictionnaire raisonné (Viollet-le-Duc, 1854-1868). Our working samples were chosen from among rose tracery designs of 12th- and 13th-century Île-de-France (Hardy, 1983). They range from simple oculi to double wheel-windows. Our primary interest has been to formulate the process most likely to have led to the realization of such designs, whose forms may be most easily understood as the result of the interlocking of solids and voids within an encompassing circular frame. To date, the two most basic stages of our work have consisted of, first, the reconstruction of the design process (i.e., the iteration of the compositional logic of rose window design) and, second, the making of a computer model of this process. 4. UNDERSTANDING THE DESIGN PROCESS As with any art object, Gothic rose windows are usually perceived as global, unified Gestalten. In actual fact they are heterogeneous in form and material and reflect, however dimly, a complex process of creation (parts of which elude us today for having left little or no trace in their temporal wake) that was also certainly heterogeneous in the diversity of the steps of which it was comprised. When one comes to speak of the working methods of medieval builders the evidence is rather slim. The only known architectural drawings in the modern sense date back no further than the Late Gothic period. For the earlier period we have only a smattering of full-scale working “drawings”, in the form of wall or floor tracings. These “drawings”, today few in number and often incomplete, were incised with a metal point directly onto the floor or wall of the building being constructed. Frequently, they were little more than sketches, but they also often served as working drawings on the basis of which templates for stonecutting could be made. Despite their rarity and limited function, these tracings supply us with certain precious indications as to the way designers made use of geometry in their designs (Fig. 2).